1. Field of the Invention
The present invention relates, in general, to lancing devices and, in particular, to lancing devices with penetration depth control and associated methods of use.
2. Description of the Related Art
Conventional lancing devices generally have a rigid housing and a lancet that can be armed and launched so as to briefly protrude from one end of the lancing device. For example, conventional lancing devices can include a lancet that is mounted within a rigid housing such that the lancet is movable relative to the rigid housing along a longitudinal axis thereof. Typically, the lancet is spring loaded and launched, upon release of the spring, to penetrate (i.e., “lance”) a target site (e.g., a dermal tissue target site). A biological fluid sample (e.g., a whole blood sample) can then be expressed from the penetrated target site for collection and analysis. Conventional lancing devices are described in U.S. Pat. No. 5,730,753 to Morita, U.S. Pat. No. 6,045,567 to Taylor et al. and U.S. Pat. No. 6,071,250 to Douglas et al., each of which is incorporated fully herein by reference.
Lancing devices often include a cap that engages the target site. Such a cap has an aperture (i.e., opening), through which the lancet protrudes during use. Typically, a distal end of the cap will be placed in contact with the target site during use. The profile of the distal end of the cap can be adapted for contact with predetermined target sites, such as fingers, earlobes, forearms and the abdomen.
When a cap is contacted with a target site, pressure is usually applied to the target site prior to launch of the lancet. This pressure urges the cap against the target site and creates a target site bulge within the opening of the cap. The lancet is then launched to penetrate the target site bulge.
When pressure is applied on a cap of a lancing device against a target site, however, the height of the resultant target site bulge can vary greatly depending on the dimensions of the cap's opening, the magnitude of applied pressure and various physical properties (e.g., elasticity) of the target site. Such variability in target site bulge height causes the penetration depth of the lancet into the target site bulge to vary, as well. Thus, a lancet can potentially penetrate too deeply in some circumstances and not deeply enough, or at all, in other circumstances. Still needed in the field, therefore, is a lancing device and associated method that provide for the control of penetration depth across target site bulges of various heights.